macOS ships with an old system Python you shouldn't rely on. Install a fresh one:

Option A — official installer (easiest): download Python 3 from python.org/downloads, open the .pkg, and follow the steps.

Option B — Homebrew (if you have it):

brew install python

Then open the Terminal app and check:

python3 --version

On macOS you'll often type python3 (not python). If it prints Python 3.x.x, you're ready.